National and international studies have revealed that significant numbers of adolescents do not adequately comprehend complex texts, impeding their success in school, access to post-secondary learning, and employment opportunities within our increasingly competitive work environment (Biancarosa & Snow, 2004; Kamil, Borman, Dole, Kral, Salingner, & Torgesen, 2008). Thus, the purpose of this application is to request support for five years of mentored research through the NIH Mentored Clinical Scientist Research Career Development Award (K08) in order to better understand why adolescent readers fail to understand the material they read. The training plan will focus on the following areas: (1) cognitive, developmental, and neuropsychological theories/models of comprehension and learning; the design of basic cognitive experimentation for the purpose of identifying language, text-specific, and domain general cognitive processes that influence language and reading comprehension development (primary mentor: Barnes); (2) the design of theoretically motivated, reliable, and valid measures of text-level cognitive processes [and advanced training in measurement, IRT, multi-level modeling, and experimental design] (mentor: Francis); (3) the integration of this information to design, conduct, and evaluate interventions for adolescent poor comprehenders (mentor: Vaughn); and (4) grant writing and development of a strong publication record (mentor: Fletcher). The research plan has 3 specific aims that will focus on (1) the language, text-level cognitive processes, and neuropsychological processes that underlie reading comprehension, (2) the skills that underlie inference making and the integration of information, and (3) the design of reliable and valid measures of inference making and integration of information.